Sandblast stencil and method of making the same



Sept. 19, 1944. HELGESQN 2,358,710

SANDBLAST STENCIL AND METHOD OF MAKING THE SAME Filed June 27, 1941 20 V I9 I 1.5a \J 5; :aa :23

4o l lAROLD R. HELGESON Patented Sept. 19, 1944 UNITED SANDBLASTSTENGE AND OF MAKINGTHESAME Harold It. Helgeson, StLLPaul, Minn. V ApplicationJune 194i, Serial No. ill (L129 Q v 1 deal. (c1. 41*390 My invention relates to an improvementin 'sten oils and more particularly that type of stencil used in sandblasting work and also relates to the manner inwhich the stencil is prepared for use.

In forming stencils for sandblasting designs upon work surfaces and the like, it has been common practice to coat the surface of the work either' with a stencil sheet formed of sandblast resistant material, o'rto coat this surface with a coating-of glue or the like which is resistant to the force (if a sandblast so that a design may be formed by cutting away portions of the glue.-

' 'It isa feature of the present invention to pro vide a stencil which isformed ofsandblastres'istant material and yet which is sufiiciently rigid so that the stencil may be merely held in place by clamps or other suitable means durihgthe sandblast operation to obviate the necessity of carving the stencil upon the work or adhering the carved stencil to the Work.- Thus in forming a series of panels or the like-having similar designs; it is possible to carve a greater number of designs in a given amount of time due to'the elimination of the previously necessary steps of carving numerous stencils'or of attaching the stencil to the work.

The applicant has produced amethod of forming rigid stencils which consists in carving a stencil' sheet in the ordinary way, mounting this stencil upon a rigid backing sheet, either before or after the cutting operation, and sane blasting the rigid backing sheet through the stenin] design to remove the exposed portions of the backing sheet visible through the stencil. Thusa rigid stencilisformed which may be used a great number of times, the rigid body which is relatively non-resistant to sandblast being protected by the resistant stencil sheet coating. With such a stencil a great number of duplicate designs may be carved in a small amount of time as it is only necessary to hold the rigid stencil firmly against the work being carved during the sandblasting operation.

' It is a feature of my invention to provide a stencil comprising a layer of material resistant to sandblast and a layer of material which is relatively nonresistant to the sandblast and to form the stencil by cutting the resistant portion of the stencil and by sandblasting the nonresistant portion of the stencil. Thus a rigid stencil may be formed with virtually as great ease as a nonrigid stencil, and for all practical purposes this rigid stencil is as resistant to sandblast as a stencil formed entirely of resistant material.

It is a: feature ofmy invention to. provide a meansof forming duplicate designs by clamping the rigid stencil against the'wo'rk to be carved and'sandblasting the work. through the. clamped stencil thus supported; Thisx'clamp may be of various forms, and may be of a type which engages the stencil about the peripheral edge of the same, or may be of a type which engages against the particular area of the work being sandblasted at any one time. means may be so arranged as to move over the surface of-the work as the sand-blasting nozzle is raised or lowered so that the'clamping means-remainsin operative relation to thesandblasting nozzle. I N These and other objects andnovel features. of my invention will be more clearly and fully set forth in the following specification and claim. In the drawing forming a part of my specification:

Figure 1 is a perspective view of a stencil upon completion thereof. I v a a s Figure 2 is a cross-seetional viewof the stencil during the forming process of the same, Figure 3 is a cross-sectional view similar to Figure 2 showing the stencil after-the rigid backing sheet thereof has been out through by the sandblasting precess;- 1 a 1 I Figure 4 illustrates the stencil clamped in place showing the operation of sandblastinga surface through the stencil. Y I Figur.5 is a diagrammatic 'cross sectional view through a stencil and sandblas't curtain inustr'aa ing the manner in which-the clamping means for the stencil moves with the sandblasting nozzle. Figure 6 is a view taken within the curtain and the clamping means therefor;

In the preparation of the stencil A; I provide a stencil sheet I0 formed of rubber or other sim ilar resilient material resistant to a sandblast. A desired design H is cut into the sheet III, which design is to be sand-blasted upon any desired workingsurface; The resistant sheet i0 is se cured to a rigid-backing sheet I2 by an suit: able means such asthe adhesive [3Q The sheet l0 may be applied-to the rigid backing sheet either before or after the stencil" has "been cut. e rigid backing sheet inafy-be or'any suitable material such as pressed'w'cfod'or any'type" of artificial or natural wood or pulp product which is rigid in formand which is relatively nonresistant to the sandblast.

After the desired design II has been cut into the stencil sheet III, as illustrated in Figure 2 of shown in Figurefi and ldoking beware the stencil This latter type of clamping forcing sheet l2. The covering of resistant stencil materialformed by the sheet I protects the portions of the reinforcing board l2 over which it extends, and thus a rigid stencil is provided which may be formed virtually as quickly as the original wound upon a drum or roller 31. The cables or ropes 35 pass over th pulleys 39 and are wound upon the drum or roller 40. A belt or chain 4| connects sprockets 43 and 44, respectively, rotatable with the rollers 31 and 40 to move these rollers in unison so that as the cable 34 is wound upon the drum or roller 31, the rop or cable 35 is unwound from the drum or roller 40. Similarly when the cable 35 is woundsupon the drum 40, the cable 34 is unwoundfromjthe roller 31 A sandblasting curtain 42 is wound upon the roller 31 or a concentrically mounted roller. This curtain extends down and is wound upon the drum stencil sheet I0 may be out, as the sandblasting operation shown in Figure 3 requires an 'extremely short period of time. 7

In the use of the stencil A, this stencil may be supported overlying a surfac l6 of a body of material I! upon which the sandblast design is to be carved. Clamping fingers such as l9 may overlie the marginal edges of the stencil A and may be held in place by the clamping screw 20. Thus by means of the'clamping means 19 and 20, the stencil A is held'closely adjacent the surface [6 of the work body l1 and it is not necessary to adhere the stencil to the work surface. As shown in' Figure 4 of the drawing, the bodies of material I! which are sandblasted, may be of substantially uniform size and may fit within a clamping arrangement including the back board 2 Land the sides 22 to which the clamping fingers l9 are attached by the clamping screws 20.- In order to sandblast the surface l6 it is thus only necessary to insert the body of material I! in place, to apply the stencil A over the surface l6, and to clamp the st'encil in place by means of the clamping fingers I9 and the screws 20. When the sandblasting. operation has been completed; the work I! may be as quickly removed by loosening the clamping members l9 and and removing the stencil A and the work body I I. y e

In Figures 5;.and 6 ofthe drawing, I disclose a modified form of clamp which is adjustable in combination with the sandblasting curtain and the nozzle .used in conjunction therewith. In this form of construction which is diagrammatically illustrated, the backingmember 23 is proyided with supports 24 of an type by means of which the material 25 to be sandblasted may be supported. The supports 24 may be adjustable on the backing wall 23, or the work 25 may be supported in any convenient manner upon the backing member 23. The stencil A is placed over the surface 26 of the material 25 and is held against materialto be carved by a series of sets of rollers 21 and 29'. The miner -2e as indicated in Figure 6 are mounted upon a shaft 30, while the rollers 21 are mounted upon a shaft 3|. A pair of connecting links 32 support the shafts 30 and'3l, and the rollers 29 and 30 are urged against the stencil A by means of springs 33 which urge the links 32 toward the backing member 23.

In order to raise and lower the clamping means indicated generally by the letter B, I provide ropes or cables 34 secured to the upper extremity of the links 32 and ropes or cables 35 secured to the lower extremity of the links 32. Th 'ropes or cables 34 extend over the pulleys 36 and are or roller 40 or a concentrically mounted roller movable therewith. As the drum 3'! moves in a clockwise direction, the curtain 42 will be un- I wound from the roller 31 and will be wound upon v the drum 4!). As the roller 31 moves in a counterclockwise direction, the curtain 42 will be wound upon this roller 3'! and will be unwound from the roller 40.- v Th curtain 42 is provided with a nozzle aperutre 45 through which the sandblasting nozzle 46 may extend. The aperture 451's directly opposite the space between the spaced shafts 30 and 3|. Thus the sandblast from the nozzle 46 i directed against the area of the stencil A between the two sets of rollers 21 and 29. i

Inoperation, after the work 25 and the stencil A have been placed inposition and the rollers 21 and 29 have been mounted to move over the surface of the stencil, the sandblast nozzle 46 is inserted through the apertur 45 and the area of the stencil between the shaft 30- and- 3| is subjectedto a blast of sand. As the work 25 is cut or carved by the sand to the properdepth, the

curtain is moved downwardly, the rollers 21 and 29 moving downwardly simultaneously so that the area between the shafts 30 and 31 is always opposite .the nozzle 46. the-entire area of the stencil maybe sandblasted, and the stencil is clamped by the rollers 21 and23 firmly against the work surface at all times. 7

In accordance with the patent statutes,-I have described the principles of construction and operation of my stenciland the'method of forming and using the same; and while I have endeavored to set forth the best embodimentsthereof, I desire to have it understood that obvious changes may be madewithin the scope of the following claim without departing from the spirit of my invention. I .Iclaim:

A method of forming stencilsfand sandblast: ing designs which consists in forming in a sandblasting resistant plate a series of openings comprising a, fiure, permanently, securing a rigid backing plate to "the stencil. plate,-'directing a sandblast upon the stencil sheet and the openings therethrough, whereby the backing plate is perforated in exact duplication of the design cut in the stencil plate, thereafter lockin the stencil assemblage upon a platein which the design is to be cut, subjecting the stencil .plate and said last named plate to the action of the sandblast,

' and releasing the stencil plate combination and CERTIFICATE OF CORRECTION. Patent No. 2, ,710. September 19, 19th.

HAROLD R. HELGESON.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction'as follows: Page 2, sec- ,ond column, line 57, claim 1, for "iiure" read -figure--'; and that the saidLetters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 5th day of December, A. D. 19M.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

